1. Technical Field
The present disclosure relates to an antenna element and a semiconductor device, particularly, to an antenna element and a semiconductor device used in wireless communication.
2. Background Art
In semiconductor devices used as a module for wireless communication, a semiconductor device has been known which has an antenna element or an antenna pattern as shown in FIGS. 1 and 2.
FIG. 1 is a cross-sectional view illustrating the semiconductor device in the related art.
Referring to FIG. 1, a semiconductor device 200 includes a wiring substrate 201, an electronic component such as a CPU chip 203, an RF device 204, and matching components 205 and 206, and an antenna element such as a chip antenna 208.
The wiring substrate 201 has a substrate body 211 and wires 213 to 218. The substrate body 211 is a substrate for forming the wires 213 to 218. The substrate body 211 may be made of resin. The wires 213 to 218 are disposed on the substrate body 211.
The CPU chip 203 is flip-chip bonded to the wires 213 and 214. The RF device 204 is flip-chip bonded to the wires 214 and 215. The RF device 204 is electrically connected to the CPU chip 203 through the wire 214.
The matching component 205 is formed on the wiring substrate 201, and is electrically connected with the wires 215 and 216. The matching component 205 is electrically connected to the RF device 204 through the wire 215. The matching component 206 is disposed on the wiring substrate 201, and is electrically connected with the wires 216 and 217. The matching component 206 is electrically connected to the matching component 205 through the wire 216. The matching components 205 and 206 are components for adjusting impedance of the chip antenna.
The chip antenna 208 is disposed on the wiring substrate 201, and is electrically connected with the wires 217 and 218. The chip antenna 208 is electrically connected with the matching components 205 and 206. The chip antenna 208 is a component thicker in thickness than the CPU chip 203, the RF device 204, and the matching components 205 and 206. For example, a plurality of green sheets (which are changed into a ceramic plate after a sintering process) having conductors (which are changed into an antenna after the sintering process) formed thereon are laminated and subsequently the laminated plurality of green sheets are sintered, and thus the chip antenna 208 can be formed. (see e.g., Japanese Unexamined Patent Application Publication No. 2001-119224)
FIG. 2 is a cross-sectional view illustrating another semiconductor device in the related art. In FIG. 2, the same elements as the semiconductor device 200 shown in FIG. 1 will be referenced by the same reference numerals and signs.
Referring to FIG. 2, another semiconductor device 220 includes a wiring substrate 221, electronic components such as a CPU chip 203 and an RF device 204, and an antenna element such as an antenna pattern 223.
The wiring substrate 221 has a substrate body 211 made of resin and wires 213 to 215. The antenna pattern 223 is disposed on the substrate body 211. The antenna pattern 223 is formed by a wiring pattern. The antenna pattern 223 is connected to the wire 215. The antenna pattern 223 is electrically connected to the RF device 204 through the wire 215. A thickness of the antenna pattern 223 may be set to, for example, 20 μm to 30 μm. In addition, when the semiconductor device 220 is used at a frequency of 2.4 GHz, dimension of the antenna pattern 223 in plan view may be set to 10 mm×24 mm (see e.g., Japanese Unexamined Patent Application Publication No. 2004-22667).
However, since the chip antenna 208 is formed by laminating a plurality of ceramic plates having conductors formed thereon, there is a problem that it is difficult to decrease a size in thickness direction thereof.
In addition, when the chip antenna 208 is used as an antenna element, a size increases in thickness direction of the semiconductor device 200. Thus, it is difficult to decrease the size in thickness direction of the semiconductor device 200.
In addition, in the semiconductor device 220 in which the antenna pattern 223 is used as an antenna element, the matching components 205 and 206 are not required. Thus, it is possible to decrease the size of the semiconductor device 220 to be smaller than the size of the semiconductor device 200 in the thickness direction. However, since the antenna pattern 223 is formed on the substrate body 211 made of resin (a dielectric constant of resin is 4) having a low dielectric constant, a size of the antenna pattern 223 formed on the substrate body 211 increases in surface direction thereof. Therefore, there is a problem that it is difficult to decrease a size in surface direction of the semiconductor device 220.